1. Field of the Invention
The present invention generally relates to fastening means and more particularly to the improved fastener driving tool and to an improved dimpler attachment for the same.
2. Prior Art
Various types of fastener driving tools have been devised. Most do not incorporate means for dimpling the area around the fastener. See, for example, U.S. Pat. Nos. 3,106,136; 2,995, 113; 2,585, 939; 2,887,686; 4,091,981, 3,001,169; 2,679,044; 4,040,554, and 4,068790. However, in order to attach gypsum wallboard and the like to wooden structural members, building codes, fire codes and gypsum board manufacturers, among others, generally require the completed fastening process to have the following properties:
1. The head of the fastener must be forced below the surface of the surrounding wallboard in order to allow wallboard compounds to be placed over and completely conceal the fastener; PA1 2. The head of the fastener should be seated in the bottom center of a dimple adapted to contain the wallboard compound; PA1 3. The head of the fastener must not break the paper surface of the wallboard; and PA1 4. The wallboard must be drawn as tightly against the wooden structural members as possible.
The lack of means to effectively dimple to meet the above requirements has rendered many conventional fastener driving tools unsuitable for wallboard applications. It would be desirable to be able to easily, inexpensively add dimpling means to such devices.
Certain fastener driving tools, however, do include dimpling members. See, for example, U.S. Pat. Nos. 3,774,293; 3,040,327; 3,027,560; and 2,918,675. Most such devices still have one or more deficiencies. Thus, in some cases, the tools are heavy, cumbersome, complicated and expensive, depending on, in some instances, separate power activators for the fastener driver and dimpler.
U.S. Pat. No. 3,774,293, discloses a device which in operation tends to have the driver bounce the tool and dimpler away from the substrate so that light and variable dimpling may occur. There is no positive retention of the dimpling head against the substrate during dimpling and fastener seating. In some instances, the driving and dimpling actions are so uncoordinated that the fastener is only driven to the level of the substrate and the dimple is then made around it, so that the fastener projects up above the base of the dimple.
U.S. Pat. No. 3,040,327 discloses a fastener driving and dimpling tool which does not have means to gradually and effectively slow the driver while transferring energy to the dimpler, so that slap and bounce of the tool can occur during its operation, with variable results.
U.S. Pat. No. 2,918,675 discloses fastener driving and dimpling tool with no energy cushioning means whatsoever, and consequently subject to bounce and erratic results.
U.S. Pat. No. 3,027,550 discloses a dimpler mechanism with complicated biasing means for keeping the dimpler out of an operative position until desired, but again, with no energy cushioning means and also subject to erratic results.
Accordingly, there is a need for an improved, simpler inexpensive and efficient fastener driving and dimpling tool which works smoothly and with proper coordination of the driver and dimpler to uniformly fully seat the fastener in the base of the dimple without damage to the wallboard covering. Preferably, the tool dimpler attachment should be capable of being separately mounted on and utilized with conventional fastener driving tools not having dimpler mechanisms. Such tool should be capable of being dry fired without damage. Moreover, the head of the fastener delivered by the tool and the dimpler should not rupture the wallboard covering (paper or the like) if during such penetration the structural member backing the wallboard is missed. Preferably the tool should be capable of accepting thin headed fasteners and of delivering fasteners and dimpling into tight places such as corner.
The weight of the dimpling head should be substantial enough to have sufficient inertia to draw the gypsum wall board and wood member together.